Most Common Sources of Anesthesia Litigation in the OR

A Meta-Analysis of the ASA Closed Claims Project

Case Law Index · Meta-Analysis · Closed Claims

TL;DR

The American Society of Anesthesiologists Closed Claims Project has reviewed nearly 9,000 malpractice claims since its founding in 1984, making it the largest standardized database of anesthesia-related patient injury in the world. Four damaging-event categories explain roughly two-thirds of all claims: respiratory events, regional block injuries, cardiovascular events, and equipment-related events. The most consequential finding across decades of data is simple: the majority of severe injuries are judged preventable by better monitoring, which is why pulse oximetry, capnography, and vigilance are not just clinical preferences but the legal standard of care.

Context

The Database

The ASA Closed Claims Project was founded in 1984 in response to a crisis: anesthesia malpractice premiums had spiked so sharply that providers were nearly priced out of practice. At the time, anesthesia accounted for roughly 11 percent of malpractice dollars paid out in medicine, despite anesthesiologists representing only about 3 percent of the physician workforce. The project was created to study these injuries systematically and figure out what was actually going wrong in the operating room.

A “closed” claim is a malpractice case that has been fully resolved, either by settlement, verdict, or dismissal, which means the full record (medical chart, depositions, expert opinions, payment data) is available for review. The database now contains roughly 9,000 claims spanning more than four decades.

The Method

Each claim is reviewed by trained anesthesiologist reviewers using a standardized data collection form. Reviewers code the case for patient demographics, anesthetic technique, the damaging event (the specific thing that caused the injury), severity of outcome, whether the care met standard, and whether better monitoring would have prevented the injury.

From this we can see that the database is not a record of every anesthesia injury that has ever happened; it is a record of every anesthesia injury that became a lawsuit and then closed. This is an important distinction because it means rare-but-catastrophic events are over-represented, while minor injuries that never reached litigation are invisible to the dataset.

Scope of Analysis

This analysis focuses on intraoperative claims: events that occurred while the patient was under anesthesia in an operating room, across all three major anesthetic modalities (general anesthesia, monitored anesthesia care, and regional anesthesia). Obstetric, chronic pain, and acute postoperative pain claims are tracked separately by the project and are excluded here.

The reason for this scope is that the operating room is where anesthesia providers spend the majority of their clinical time, and the litigation patterns there are the most directly tied to the day-to-day decisions a CAA, CRNA, or anesthesiologist makes during a case.

Distribution of Damaging Events

What Actually Gets Sued

A “damaging event” is the specific clinical occurrence that caused the patient’s injury, not the injury itself. For example, a patient with anoxic brain injury may have suffered the injury because of an esophageal intubation; the brain injury is the outcome, but the esophageal intubation is the damaging event. Across the modern dataset, four categories account for roughly two-thirds of all surgical anesthesia claims:

Respiratory events (17–25%): the historically dominant category, including difficult intubation, esophageal intubation, inadequate oxygenation or ventilation, aspiration of gastric contents, and bronchospasm. These are the events most directly tied to airway management, which is why they remain a central focus of training and standard-of-care discussions.
Regional block-related events (19–20%): injuries caused by the technical performance of neuraxial (spinal, epidural) or peripheral nerve blocks. This includes needle trauma to nerves or the spinal cord, high spinal blocks producing cardiovascular collapse, and neuraxial hematoma in anticoagulated patients.
Cardiovascular events (13–14%): excessive blood loss with inadequate fluid replacement, air or fat pulmonary embolism, intraoperative myocardial infarction, and hypotension severe enough to cause end-organ injury. Cardiac events are the second most common cause of death and brain damage claims in the modern era.
Equipment-related events (10–11%): failures or misuse of anesthesia machines, breathing circuits, infusion pumps, and monitors. These are most prominent in cardiac surgical claims, where the complexity of the equipment array (bypass machines, transesophageal echo, multiple infusion lines) raises the chance of a device-related failure.
Medication-related events (~5–10%): wrong drug, wrong dose, syringe swaps, drug allergies not screened for, and dangerous polypharmacy combinations (e.g., propofol layered with opioid and benzodiazepine during MAC). The standardized syringe labels you see in every OR are a direct response to this category.
Burns, positioning injuries, and awareness (~5% each): fires from electrical sparks near supplemental oxygen, peripheral nerve injuries from improper limb positioning, and intraoperative awareness with recall under general anesthesia. Smaller individual slices but consistent contributors year over year.

Mechanism of Injury

Mechanisms Behind the Top Claims

If we look across the four dominant damaging-event categories, a pattern emerges. The most consequential mechanism of injury (the one most likely to produce death or permanent brain damage) is almost always the same: inadequate oxygen delivery to vital tissues, whether that comes from a respiratory event, a cardiovascular event, or a regional block that drops perfusion pressure too far. From this we can see why monitoring is the throughline.

Respiratory: the lung gas exchange surface goes offline, either because the airway is blocked (difficult intubation, oversedation, bronchospasm) or because the tube is in the wrong place (esophageal intubation). Oxygen delivery to the blood drops, and within minutes the brain is at risk.
Regional block: the local anesthetic ascends higher than intended (high spinal) or directly injures a neural structure. A high spinal blocks the sympathetic outflow that maintains vascular tone, producing sudden hypotension and bradycardia that can collapse perfusion if not treated immediately.
Cardiovascular: the pump or the pipes fail. Massive blood loss, embolism, or myocardial infarction all share an end pathway of reduced cardiac output, which means even an oxygen-saturated lung cannot push that oxygen to the tissues that need it.
Equipment: the monitor that should have caught the problem either failed, was misused, or was not turned on. The standardized way to catch problems early can be achieved via continuous pulse oximetry and end-tidal capnography, the two monitors most directly tied to the modern reduction in claims.

Why Monitoring Changed Everything

In the 1970s, respiratory events accounted for roughly 36 percent of all claims, with esophageal intubation and inadequate ventilation as the leading offenders. By the 1990s, that number had fallen to about 14 percent. What changed in between was not surgical technique or drug pharmacology; it was the routine availability of two devices: the pulse oximeter (a finger-clip sensor that reports arterial oxygen saturation in real time) and the capnograph (a sensor that measures exhaled carbon dioxide and confirms the endotracheal tube is in the trachea rather than the esophagus). The ASA adopted pulse oximetry as a basic intraoperative monitoring standard in 1990, end-tidal capnography for verifying intubation in 1991, and capnography during MAC in 2011. The legal standard of care followed the technology, and the litigation profile shifted with it. The brain has roughly a four-to-six minute window before oxygen deprivation produces irreversible injury, and monitoring exists to make sure that window is never opened.

Common Failures

Across the four dominant damaging-event categories, plaintiffs allege a recurring set of standard-of-care breaches. These are not the only allegations in any given case, but they are the ones that show up most often in the reviewers’ coding:

Failure to monitor: required monitors (pulse oximetry, capnography, blood pressure, ECG) were absent, turned off, alarming silently, or not being watched at the moment of the event.
Failure to rescue: the abnormal vital sign was present in the chart but not recognized or not acted on in time, allowing a recoverable physiologic problem to progress to cardiac arrest or brain injury.
Inadequate supervision: the supervising anesthesiologist was not present, not immediately available, or not actively engaged at the critical moment, leaving a CAA, CRNA, or resident to manage a deteriorating patient without backup.
Inadequate preoperative assessment: a risk factor that should have changed the anesthetic plan (morbid obesity, obstructive sleep apnea, difficult airway predictors, anticoagulation, severe cardiac disease) was not identified or not acted on.
Inadequate informed consent: the specific risk that materialized was not discussed with the patient beforehand, removing the “the patient knew and accepted this risk” defense entirely.
Medication error: wrong drug, wrong dose, wrong route, or dangerous combinations (especially polypharmacy during MAC, where propofol, opioid, and benzodiazepine produce supra-additive respiratory depression).

The Outcomes

When the project codes injury severity, the distribution across the modern dataset breaks down roughly as follows:

Death: approximately 26% of claims.
Nerve injury: approximately 22% of claims, with spinal cord injury emerging as the leading nerve injury subtype in the 1990s and beyond.
Permanent brain damage: approximately 9% of claims, almost all traceable to a period of inadequate oxygen delivery.
MAC-specific severity: roughly 40% of claims involving monitored anesthesia care resulted in death or permanent brain damage, comparable to general anesthesia and far worse than regional anesthesia. Respiratory depression from oversedation was the single most common mechanism, present in about 21% of MAC claims.
Payment frequency: payment was made in roughly 52% of general anesthesia claims and 57% of MAC claims, with median payments in the six-figure range.

Reflection

The Closed Claims Project is, in effect, a forty-year experiment in what happens when an entire specialty takes its own malpractice data seriously. The lesson it has produced, over and over again across damaging-event categories, is that most severe anesthesia injuries are not the result of exotic complications but of routine ones caught too late. The pulse oximeter and the capnograph did not eliminate human error; they shrank the window in which human error could compound into anoxic brain injury. Every monitoring standard now considered basic was, at some point, somebody’s closed claim.

References